Massive eruption in Tonga

[bjdeming]

This article puts it in perspective. The scientists' minds were boggled, too.

“The first thing we did was a circle around the volcano, and I’m going, ‘What the hell?’” recalls Kevin Mackay, a marine geologist at NIWA who led the expedition. “It just defied expectations.”

Here's video from the second survey, in the smaller craft, to map the caldera.

 

[bjdeming]

Meanwhile, atmospheric effects of the blast linger, at least regionally.



Gorgeous!

I haven't noticed much change at this latitude -- granted, we've had a cloudy cold spring (thanks, Alaska! ).

Has anyone in the lands of Sun noted any changes? Simon Carn did tweet a while back that the stratospheric sulfur veil was spreading meridionally -- slowly.

 

[bjdeming]

There have been some M5 to 6-ish quakes in the general area since May 30th, but thus far I've seen no authoritative mention of any links to Hunga.

The USGS did post this article a couple days ago, which included this (which applies to any atmospheric phenomena -- they mention squalls -- though it takes something really intense for Lamb waves):

So how do atmospheric conditions create meteotsunamis? “A sharp increase in air pressure will push the sea surface down and vice versa,” said Geist. “One millibar of pressure change will generate about 1 centimeter [about 3/8 inch] of up or down change in the ocean’s surface,” creating water waves that oscillate from 1 centimeter above to 1 centimeter below sea level. Geist uses the word “coupled” to describe water waves created and pushed along by atmospheric waves.

“One or two centimeters isn’t that big,” Geist said, “but if the atmospheric disturbance—it could be a line of squalls or, in this case, atmospheric waves triggered by the eruption—if it’s moving close to the speed that tsunami waves would naturally travel, resonance effects will amplify the coupled water waves and make them much bigger.”

Speed and water depth are keys to resonance​

The speed that tsunami waves naturally move through the ocean depends on depth: the deeper the water, the faster the tsunami waves. For 700 mph atmospheric Lamb waves to build up large tsunami waves through resonance, you need depths in which tsunami waves would naturally travel near 700 mph. That requires water about 6 miles deep. For the somewhat slower atmospheric gravity waves to build up significant tsunami waves would require water depths of around 4 miles.

The average depth of the Pacific Ocean is only 2½ miles, so the water waves moving along with atmospheric waves generated by the eruption stayed almost imperceptibly low as they traveled across the Pacific toward Japan. But as the coupled ocean and atmospheric waves got closer to Japan, they began traveling over much deeper water—the Mariana Trench off Japan is almost 7 miles deep. Scientists hypothesize that as the waves swept over the deep ocean near trenches, resonance between the atmospheric waves and the ocean was sufficient to amplify the water waves and increase their height.

 

[bjdeming]

This morning I recorded some optical effects around sunrise -- the first relatively clear one I've seen in a while.

Hope a playlist works:



Details in the blog post.

The skies are always glorious near the Gulf, but has anybody noticed these unusual glows, "sun-dog" effects, purples, etc.?

 

[bjdeming]

They're certainly getting gorgeous effects in New Zealand.

It's still not clear enough to look for visual effects here (seriously, Gulf of Alaska, what did we do to deserve all these lows? )

Last night, after 10 p.m., I did notice that the western horizon clouds were still glowing bright red in a wide band -- seemed broader than usual, but I haven't paid enough attention to the sky to really know what the baseline is.

I'd look for purples and other unusual colors, plus a very wide glow -- if the skies would clear.

 

[bjdeming]

Well, last evening was partly cloudy but with a swath of clear sky in the west. Got the phone out and watched for about half an hour at sunset.

The video is of too poor a quality to share, but there were no dramatic views anyway. Overall it appeared to be a normal sunset with these exceptions:

1. A much wider span of brightness and orangey colors, all the way into the north, roughly 90° from where the sun went down. This was still visible, though not particularly illuminating, long after the street lights came on.

2. Buildings hindered my view from that third-floor window to the south, but I could see a ways past the "sundog position" left (south) of the point of sunset on the horizon - don't want to include degrees from the optics of sundogs because I was estimating everything, not being precise.

It did seem brighter, there on the left, and the camera picked this up even more than what I could see. It was diffuse glow, though, and while not anything I've typically seen at sunset anywhere, it faded with the sunset.

Unlike my view on sunrise the other morning, there didn't seem to be a bright spot at the corresponding "sundog position" on the right (north); just extensive bright twilight glow.

3. That glow on the left (south) looked very orange to me, though it seems whiter on video. But this orangeness moved around all over the sunset field during that half-hour, which definitely was atypical. Again -- just a broad area of color that moved very slowly but majestically and seemingly randomly, like aurora (which this wasn't, of course). It was too faint to try to follow the pattern of movement objectively, but it was there.

That's all there was. My layperson impression: Yes, aerosol is up there but not in such quantities as to dramatically affect the light like in New Zealand right now. And at the end of the day, with a more turbulent, particle-laden troposphere, it just wasn't possible to catch the very faint purples and greens, etc., that did show in the morning; this probably widened/diffused the "sundog-position" effect, too.

In each case, though, that effect appeared stronger and more lasting on my left, despite different viewing position, whether facing the sunrise (where it was in the north) or the sunset (south). I don't understand that.

Still, this is much better than having enough sulfate aerosol up there to affect climate a la Pinatubo and Tambora!

 

[bjdeming]

The Hunga aerosol effects in west central Oregon are intensifying, though they don't yet compare to what's been reported in the southern hemisphere.

The main effect in the evening now is a bright orange glow that lingers after sunset and ranges in equal intensity from the SSW to true north.

Last night I didn't think of doing the Krakatoa 1883 test (reading a newspaper by glow at night) until after I went to bed and then was too lazy to get up and walk to a west-facing window.

But I woke up early this morning, fortunately, and noticed what really looked like a rainbow rising in the north.

The very basic Tracfone camera doesn't do it justice. It was faint, but there definitely was the full spectrum there from red at the horizon up through orange, yellow, green, blue, and (very faintly) purple:



Now that the effect is more intense, it looks to me that this lopsided "sundog effect," always stronger to the viewer's left, is a refocussing of incoming sunlight that only occurs on the "dark side" of the terminator edge -- just as the Sun is moving out from behind the Earth (night/dawn) and again when it has just gone behind the Earth (sunset/night).

I think that stratospheric aerosol layer up there somehow interacts optically with the edge of our planet, in effect, turning it into a grating that diffracts those first/last rays of incoming sunlight, though the mathematics of why it's always at about 45° to the viewer's left are beyond me just now, at the start of a busy work day.

As the Sun moves up towards the eastern horizon (in this morning's case), that effect turns into the current unusually broad glow all along the horizon.

This morning that glow, a half-hour after the above video, extended from true north eastward and probably all the way to the SSE, though I couldn't see it from my window.



(Sorry about the unprofessional quality of these videos. Barring an unexpected boom in book sales, I'm about a year and a half away from getting decent equipment and some training in basic videography.)

We are truly lucky that Hunga's magma had a low sulfur content.

I haven't seen any scientific papers on this yet, of course, but I wonder what the boffins are thinking now about aerosol/atmosphere interactions and their effects on climate and weather.

Edit July 6th: Thanks to a summer cold messing up my sleeping schedule, I've had opportunities to check out that false dawn effect. Decided it's not diffraction since it's strongest where the terminator is "fuzziest." It's probably refraction of the first sun rays through the aerosol layer.

The sunset effects are harder to identify, other than the bright orange glow now all along the horizon.

But have you seen the images from Antarctica? Wow!

 

[bjdeming]

The eruption reportedly increased the stratosphere's water content by about 10%.

No one seems quite sure about what effects that's going to have over the next five years.

 

[bjdeming]

Stratospheric water, that is. Any thoughts from knowledgeable people about what this could perhaps do/is doing to weather and various teleconnections? From reading, it seems that we can expect this to be up there for several years.

 

[bjdeming]

Not that anyone has been breathlessly awaiting the news but we now have that predawn glow at both sundog points:



Beautiful chromatism this morning over both points, too -- again, very subtle but there.

I think the sky glowed more, too.

Also, a week or two ago, I happened to look out a west-facing window at about 2 a.m. and noticed a bright but narrow white glow all along the western horizon.

There is a town west of us (Philomath) and you can see its lights reflected during the cloudy season. This was nothing like that. It was a clear sky (lots of humidity, though) and no focal point, just the same white line on the horizon as far as I could see from that window: SSW -- WNW. At 2 a.m (sunset would have been around 9 p.m. or earlier).

Don't know if it's visible all the time or not; presumably, it is.

But that made me realize just how big this really is, even if there wasn't enough S to load the stratosphere with aerosol.

The stratosphere glows!

Am thinking that the one-sided terminator "sun-dog effect" was due to low aerosol levels then; now, there's enough above us for the full effect, and a little prismatic coloration, anyway.

I might do a blog post, though it might be too much with this other ongoing DV revision project. Eruption-atmosphere interactions are very complex and often discussed in math that's beyond my basic level.

There isn't a lot of information on volcanic water vapor injections, either: just this, basically (link to open-access study is in that article).

However, this abstract by some really big names in volcanology mentions water as well as sulfur aerosols from Krakatau 1883 and Pinatubo 1991 (a land volcano). Am going to look it up more next time I'm at OSU's public computers. (The display materials include neat graphics of Krakatau's 1883 aerosol plume estimates, BTW).

And here are a couple other papers on stratospheric water vapor and climate:

From 2020, looking at the tropical Atlantic.

From 2013, abstract, looking at feedbacks.

 

[bjdeming]

??

 

[bjdeming]

Please read the whole thread (am posting on the 27th at 6:14 am, Pacific); that recent paper mentions both the clouds and HOx reactions.

This person is in the Southern Hemisphere; I haven't looked at NH data, and frankly, couldn't say anything intelligent about it anyway (hopefully, someone here who can might be able to tell us whether or not such changes and perhaps others have been noticed).

After reading that paper, am now strongly suspecting that the optical effects overhead predawn and postsunset are more likely caused by water than sulfur aerosol.

If I understand them right, Brewer-Dobson circulation already could have brought some of that injected water this far north (and probably further).

Could changes in its vertical distribution over time, in the upper stratosphere, be why there was at first just the "left" sundog effect and now the full thing?

 

[bjdeming]

An interesting in-depth discussion on Hunga Tonga's blast effects on the SAM and Australia's summer.

 

[bjdeming]

This is so cool!

The largest volcanic eruption of the 21st century so far happened last winter, off the coast of the island nation of Tonga. Louisiana State University Department of Oceanography & Coastal Sciences Professor Chunyan Li captured it in an unexpected way—with handmade air pressure monitors from half a world away.

-- Source

By the way, we're having clear skies -- unusual but not impossible this time of year in Oregon, and I see that the gorgeous glow at sunset and dawn is still present.

Can't really tell if it has intensified, since atmospheric conditions are so different, but it sure hasn't decreased. Last night's chromatic effects at sunset were beautiful.

There's a lot of water up there, and I do wonder how it can affect Northern Hemisphere atmospheric processes.

Problem is:

1. I don't know enough meteorology to investigate online info sources efficiently.
2. As I understand it, the blast transported water into the upper stratosphere, an area that isn't as well understood as more accessible layers.

It's affecting sunlight, though -- could see that in the extended glow along the horizon last evening.

And that alone, quite apart from possible NH upper stratosphere changes, should have some effect.

Is anyone here more knowledgeable than me also curious (and too impatient to wait for the studies and papers to be completed )?

 

[bjdeming]

Submersible data coming in and, among other findings:



What's really weird is that you wouldn't have expected this from the low-level Surtseyan activity that went on for so long there.

Circumstances aligned just right, and BOOM!

 

[bjdeming]

Looks like the Southern Hemisphere is taking the bigger hit:

 

[bjdeming]

Just came across this while working up a blog post:



Per this paper (CC BY 4.0):

The HTHH eruption column produced a prodigious amount of volcanic lightning. The data we examined were summary data from the GDP360 instruments operated by Vaisala, Inc. The eruption the previous day, January 14, produced >190 000 flashes over 20 h (S. Ryan, writt. comm.). The stronger main eruption on January 15 produced >400 000 flashes in total with 200 000 flashes in the peak hour (S. Ryan, writt. comm.).

By conducting a frame-by-frame analysis of the same publicly available data (Churchill, unpublished footage) containing raw CG stroke counts by intensity, and interpolating the time of each stroke count from the underlain and correlated Himiwari-8 satellite footage, we obtained >700 000 sources (Fig. 2; Supplementary Table S1). During the strongest stage of the main eruption, the number of flashes was 80% of worldwide lightning during the most active hour! These observations are unprecedented...

Wow!

 

[Tennie]

Here's an article summarizing what has been figured out thus far about the Hunga Tonga eruption in the one year since:

The Hunga Tonga eruption of 2022

Volcanoes can be quite predictable, in a general sort of way. We know that Grimsvotn will erupt – just not when, although it is fairly likely to be within the next two years. Similarly, Mount…

www.volcanocafe.org

 

[bjdeming]

Regarding the upper stratospheric hydration (from Aussie news source with emphasis added--paper is still in peer review)

Dr. Jucker said they expected a very slight warming influence, on average, across the globe and a strong warming influence for parts of North America during their winter for the next seven years.

But he said in Australia they were expecting the opposite, due to the way heat circulates around the globe.

This included a cooling effect for Western Australia during the summer months, and northern Australia during winter.

 

[bjdeming]

I've had to dial back my presence here because there just isn't enough time right now for me to follow the weather so closely, but did want to share this from someone in New Zealand who knows a lot more about weather than I do.

Of course, he's interested in the Antarctic and winter right now, but it's reached the North Pole, too. Just saying.